1. Field of the Invention
The present invention relates to an ink jet recording apparatus expressing tones by ejecting ink droplets of a plurality of sizes.
2. Description of the Background Art
There have been various ink jet recording apparatuses which record images on a recording medium by ejecting ink droplets from the nozzle. Such an ink jet recording apparatus is disclosed for example by EPA 0437062. In the ink jet recording apparatus disclosed by the document, the size of ink droplets is changed in order to reproduce an image having tones such as a photographic image. In order to faithfully reproduce the tones of an image, the size of ink droplets must be precisely controlled depending upon the tones of pixels to be reproduced. The size of ink droplets is changed by controlling the value of the driving voltage used to drive the recording head. A high driving voltage should be applied to drive the recording head to cause large size ink droplets to be ejected, but it is difficult to precisely control the driving voltage such that ink droplets are ejected at a desired size. Conversely, the response of the driving circuit which applies the driving voltage is lowered when small size ink droplets are to be ejected.
Some apparatuses have two different size nozzles for large and small ink droplet sizes.